Bryopesanser tonsillorum Tilbrook, 2012

Dick, Matthew H., Ngai, Nguyen Danh & Doan, Hung Dinh, 2020, Taxonomy and diversity of coelobite bryozoans from drift coral cobbles on Co To Island, northern Vietnam, Zootaxa 4747 (2), pp. 201-252 : 228-230

Bryopesanser tonsillorum Tilbrook, 2012

( Fig. 12E, F )

Bryopesanser tonsillorum Tilbrook, 2012, p. 47 , figs 17–22, table 1; and synonyms therein.

Material examined. VNMN-0250 (CT-9), on SEM stub.

Measurements. AzL, 0.52–0.76 (0.633 ± 0.066); AzW, 0.41–0.67 (0.482 ± 0.068) (n = 15, 1). OrL, 0.09–0.12 (0.108 ± 0.013); OrW, 0.103 –0.123 (0.112 ± 0.011) (n = 4, 1). OvL, 0.12–0.15 (0.139 ± 0.010); OvW, 0.18–0.25 (0.218 ± 0.018) (n = 15, 1).

Description. Colony encrusting, unilaminar, sheet-like.

Zooids irregularly hexagonal, distinct, delineated by groove. Frontal wall convex, tumid, entirely perforated proximal to peristomial region with numerous small pseudopores. Primary orifice with horseshoe-shaped anter and deep proximal median sinus that is longer than broad; raised, coarsely denticulate condyles flank sinus, making proximal orifical margin convex. Non-ooeciate zooids with predominantly seven oral spines (eight seen in one zooid). Proximal to orifice, raised, imperforate, crescent-shaped ridge merging with chambers of lateral oral avicularia; ridge weakly flared around inside curvature; sometimes with raised median projection.

Avicularia paired lateral to orifice; crossbar at roughly same level as most proximal pair of oral spines. Ooecium prominent, forming shallow cap distal to orifice, often with thickened, crescentic transverse ridge. Ooecium-bearing zooids showing three pairs of spines lateral to orifice, most distal pair incorporated in proximolateral margins of ooecium.

Remarks. Species of Bryopesanser typically form small, inconspicuous colonies in crevices in coral-rubble substrata and are easily overlooked. With the raised condyles, convex proximal margin of the orifice, and deep oral sinus, B. tonsillorum is readily distinguished from several superficially similar congeners ( Tilbrook 2012).

Distribution. Broadly distributed; previously reported from the Atlantic ( Ghana), Indian ( Sri Lanka, Indonesia) and Pacific ( Philippines, Columbia) oceans ( Tilbrook 2012, and citations therein).

Figures

FIGURE 12. A–D. Microporella tonkinensis n. sp., holotype, VNMN-0248. A. Colony. B. Autozooids with and without ooecium. C. Enlargement showing orifice and ascopore. D. Proximofrontal view of autozooids with ooecia. E, F. Bryopesanser tonsillorum Tilbrook, 2012, VNMN-0250. E. Autozooids with and without ooecium. F. Enlargement showing orifice. Scale bars: A, 1 mm; B, D, 250 µm; C, 50 µm; E, 500 µm; F, 200 µm.